Microbial diversity in infections of patients with medication-related osteonecrosis of the jaw.

A central role of infections in the treatment of MRONJ patients is widely accepted. An investigation of the MRONJ lesions' biofilms as potential pathogens seems logical. We investigated the clinical data of our MRONJ patients who received surgery in advanced stage of the disease. Special attention was granted to the local colonizers harvested from osseous MRONJ specimens and submucosal putrid infections. Eleven out of 71 patients presented a spontaneous onset of the disease and for 60 out of 71 patients a trigger was detected. Breast cancer (29.6%) and prostate cancer (22.5%) were the most frequent underlying disease for prescription of an antiresorptive therapy, mostly zoledronate. Submucosal soft tissue biofilms significantly differed from biofilms harvested from the MRONJ lesions bottom, yet the most frequent bacteria were equally present in both groups: Streptococcus species (spp.), Prevotella spp., Actinomyces spp., Veillonella spp., and Parvimonas micra. The cephalosporins, cefuroxime and cefotaxime, and ß-lactam antibiotics with ß-lactamase inhibitor revealed the greatest susceptibility for the detected bacteria. The bacteria from the submucosal areas and the bottom of the infected bone presented comparable susceptibility to the common antibiotics regimes. Streptococcus spp., Prevotella spp., and Veillonella spp. present a high abundance in MRONJ lesions beside Actinomyces spp. The MRONJ lesions bottom is in many cases not infected by Actinomyces spp. The removal of the necrotic bone reduces the variety of bacteria found in MRONJ lesions, in particular at the bottom of the lesion.